1. Field of the Invention
The invention generally relates to a light emitting diode, and more particularly, to a light emitting diode having a Bragg reflector structure.
2. Description of Related Art
Recently, the light emission efficiency of the light emitting diode (LED) has been increased. On the other hand, as compared to the traditional light bulbs, the LED encompasses the following advantages: characteristics such as small volume, long lifetime, low voltage/current drive, hard to break, mercury-free (no pollution problems), and better light emission efficiency (power saving), etc. Since the foregoing advantages and the light emission efficiency of the LED have been developed rapidly in recent years such that the LED had gradually replaced the traditional light bulb, the LED had gained a great attention in the lighting and displaying field.
Enhancing the light emission efficiency is the key for the LED to be applied in different fields. Generally, a distributed Bragg reflector (DBR) structure is manufactured on one side of the LED, so as to emit part of light emitted from the emitting layer of the LED toward a predetermined emitting direction through reflection, and thus the light extraction efficiency may be enhanced. Traditionally, a material of the reflective structure includes an alloy of gold (Au)-silver (Ag)-tin (Sn). However, traditional reflective structure is unable to provide a good reflectance in various wavelength ranges. Accordingly, improving the light emission efficiency of the LED in various wavelength ranges has become an important issue to be solved by the researchers.